Microstructural and mechanical characteristic of ceramic composite coating developed by electrophoretic deposition

Abstract

Ceramic-composite coating consisted of Yttria Stabilized Zirconia (YSZ), Fe2O3 and aluminum powder has been successfully formed on Inconel 625 substrate by electrophoretic deposition (EPD). The coating density depends not only on the stability of the EPD suspension but also on the applied voltage. In the present study, a single stage voltage treatment at 60V and a two-stage voltage treatment at 30V followed by 60V of the EPD were used. A fresh green body of ceramic coating was dried at room temperature for 24 hours prior to heat-treated at temperature of 1200 °C for 4 hours with heating rate of 2°C/min using horizontal heated furnace under argon gas inert. The effect of single- and two-stage treatments on the microstructural and mechanical hardness of the coating were investigated by Field Emission-Scanning Electron Microscopy and Vickers hardness test, respectively. The elemental composition of the coating was analysed by Energy Dispersive Spectroscopy and the crystalline phases were identified by x-ray diffractometer. The results showed that a less porous structure, and therefore, higher hardness was observed on the coating formed by a two-stage voltage than that of resulting from a single-stage voltage. The crystalline phase formed on the coatings was dominated by a tetragonal phase of ZrO2.

YSZ–Al2O3 thermal barrier nanocomposites coatings: Electrophoretic deposition and characterization

“…It is well established that volumetric expansion up to 5% due to the martensitic transformation of tetragonal zirconia to monoclinic around 1200°C causes cracking and delamination of the coating limiting YSZ performance in TBC applications 36,37 . Alumina‐induced stabilization of YSZ can retard this martensitic transformation and shift the transformation temperature to higher values.…”

“…35 It is well established that volumetric expansion up to 5% due to the martensitic transformation of tetragonal zirconia to monoclinic around 1200 • C causes cracking and delamination of the coating limiting YSZ performance in TBC applications. 36,37 Alumina-induced stabilization of YSZ can retard this martensitic transformation and shift the transformation temperature to higher values. The XRD analysis suggests that the enhanced microstructural integrity of the nanocomposite coatings observed through OM and SEM studies could be due to the stabilization of YSZ via Al 2 O 3 .…”

Corrosion behavior of YSZ and YSZ/NiCo coatings on inconel 625 exposed alkali chlorides

“…The electrophoretic movement of particles stops by the substrate, and the particle density continues to increase there due to accumulation [19]. When using the gradient method in the EPD process, small particles usually deposit at a lower voltage, followed by large particles deposit as the voltage increases [20]. When the electrical conductivity of the substrate is high, the current density becomes higher, forming a potential for gradient deposition at the start of the coating to occur more quickly.…”

YSZ Termal Bariyer Kaplamanın Elektroforetik Nano-YSZ Kaplama ile Korozyon Direncinin İyileştirilmesi

“…EPD katman kalınlığının ince istenmesinin sebebi geleneksel TBK'ya kıyasla ciddi derecede kalın bir kaplama yapılmamasının istenmesidir. Dolayısıyla biriktirme süresi literatür uygulamalarındakine yakın olan 6 dakika olarak tercih edilmiştir [20], [21]. Ayrıca kısa süreli kaplama süresi farklı parametre değişiklikleri denemelerine de olanak sağlamıştır.…”